A Good Fueling

Knowing is half the battle, and Biodiesel Magazine put out at least four feature articles in 2005 on biodiesel emissions and cold flow that armed readers with valuable, objective information.
By Ron Kotrba | December 01, 2005
2005 was quite a year for biodiesel cold flow and emissions, considering several issues were showcased across various states that highlighted both topics. For instance, Minnesota's statewide B2 mandate went into effect Sept. 29, on the edge of winter's encroachment in the bitterly cold North Country. In preparation for this landmark development, a cold flow consortium was formed to study blending practices in such low temperatures. At the same time, a less positive development was taking place 1,200 miles south of the Land of 10,000 Lakes, where the state of Texas had implemented the Texas Low Emission Diesel (TxLED) regulation. TxLED disallows the sale of blended biodiesel in the 110-county non-attainment zone housing 80 percent of the state's population unless the state certifies formulations based on NOx reduction comparable to TxLED fuels. In 2005, Biodiesel Magazine took an objective look at the issues behind these events.

Dealing with the cold
Published in the Oct. 2005 issue, "Keeping the Flow" spotlighted how the industry is addressing the cold weather performance of biodiesel blends. Conventional diesel fuel has its own hurdles, possessing cloud points that vary just above or below 0 degrees Fahrenheit. To lower the cloud point temperature, blenders mix No. 1 diesel with kerosene. Thus, in the winter months, additional measures to address cold flow aren't necessary for biodiesel blends up to 20 percent. Caution is needed in the storage and transportation of B100 prior to and during blending.

The article covered many different ways to protect neat biodiesel from crystallizing and gelling. Using additives to suppress the pour point of biodiesel is a common approach to keep the fuel flowing. Another approach is to cool the biodiesel down to a certain temperature, remove the solid, saturated fractions that have gelled, leaving the unsaturated, flow-friendly remainder for cold temperature use. Fuel composition, or the concentration of saturated esters versus unsaturated esters, is the biggest determinant to the cold flow characteristics of the fuel.

Tallow-based biodiesel has the highest saturated content while virgin vegetable oil-based biodiesel has the lowest, according to most industry experts. The producer's choice of reagent alcohol in production also comes into play.

The main conclusion from the cold flow consortium's study was that biodiesel must be kept 10 degrees above its cloud point to successfully blend with diesel without shock crystallization. If, while storing and blending B100, the distribution chain can satisfy that finding, then the rest should flow nicely.

Feel it in the air
In June, July and November, Biodiesel Magazine ran comprehensive feature articles on NOx control strategies, TxLED and a wide-angled view of biodiesel emissions, respectively.

"Knocking Out NOx" focused on why the emission of NOx is an issue-assuming biodiesel blends increase NOx, which is inconclusive and dependent on many variables-and what technological advancements exist now, will soon be available or will be federally mandated to reduce NOx.

Additives are readily available in today's marketplace to reduce NOx. Most additives work by increasing cetane. Higher cetane gives the fuel better ignition quality, lower ignition delay and lower combustion temperatures to ultimately reduce NOx emissions. Homogeneous Charge Compression Ignition (HCCI) systems also help reduce "hot spots" of concentrated fuel on the pistons, which cause higher temperatures and higher NOx output. Retarding the engine timing also reduces NOx. Engine management techniques in conjunction with exhaust gas recirculation systems, diesel particulate filters, and either a NOx trap or a selective catalytic reduction device, have shown NOx reductions up to 90 percent.

"Houston, Do We Have a Problem," printed in June, detailed Texas' environmental commission's regulation outlawing biodiesel blends in the state's heavily populated 110-county non-attainment zone. For a rundown and update on TxLED, see the feature article in this issue on page 30.

"Emissions Still Matter," an article printed just last month, covered the four main components to diesel and biodiesel exhaust: NOx, particulate matter (PM), carbon monoxide and hydrocarbons. Ultimately, NOx was revisited to say that, depending on what real-world driving conditions a vehicle sees, the dynamometer test chosen could impact accuracies of results. Biodiesel is commonly touted as having great carbon monoxide and hydrocarbon reductions compared to diesel, but high percentages are less significant when base numbers are already low. According to industry experts, the greatest emissions benefit that comes from using biodiesel-outside of the global warming argument about biodiesel not releasing nearly as much fossil carbon-is the big reduction (percentage and actual) of carcinogenic PM emissions, or black soot. It is this benefit of biodiesel that will play an important role for older diesel trucks and buses-and the environment-once the new, clean-diesel vehicles hit the streets in 2007.

Ron Kotrba is a Biodiesel Magazine staff writer. Reach him at [email protected] or (701) 746-8385.
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